The present invention concerns a tool for grooving and parting and means for manufacturing same.
Cutting inserts for grooving and parting for example, are, in order to achieve narrow widths of cut, clamped in tool holders of the blade type. The term "blade type" even includes slitting cutters and circular saw blades.
U.S. Pat. No. 4,801,224 illustrates a clamping device for a cutting insert in a holder of the blade type is described, including a cutting insert which can be clamped in a slot in the blade. The cutting insert is clamped by a spring action created by deflection of a clamping finger which is an integral part of the holder. In order to press the cutting insert into its correct position in the slot, a special installation tool is used which consists of a rod with two pins in one end surface. This device functions satisfactorily but it nevertheless suffers from certain drawbacks. For example, the fact that the cutting insert itself forces the spring clamp finger upwards each time a cutting insert is mounted, causes a certain frictional wear of the contact surfaces of the clamping finger which engage the cutting insert. That wear, over a long period, damages the contact surfaces, such that the cutting insert no longer sits with the same stability which it had at the beginning. Therefore the entire the blade holder must be exchanged.
Also, in U.S. Pat. No. 4,588,333 a clamping device in a blade holder is described, according to which the cutting insert is clamped in a slot by spring action which is created by the deflection of a clamping finger which is integrated into the blade holder. According to this design the cutting insert is pressed into the insert pocket by the operator, who pushes the end surface of a hard rod or bar against the front part of the cutting insert. In a manner similar to that in U.S. Pat. No. 4,801,224 the cutting insert is then prized out by applying one of the two pins on the said rod behind the cutting insert and levering it out. Even with this design the contact surface of the holder, which acts against the cutting insert, wears each time a cutting insert is inserted or extracted. Further, even in this case, there is the inconvenience that the installation tool requires space.
EPO 0 259 847 illustrates a blade holder with a slot for receiving the cutting insert is described, plus an additional slot for the mounting of a clamping screw, which when activated forces the blade part disposed between said two slots and presses it against the cutting insert, whereby the insert is clamped. Also here a certain wear occurs when installing the cutting insert into and removing the cutting insert from the slot in which the insert is to sit. Furthermore the clamping screw can cause certain problems, by limiting the amount of play and giving inadequate clamping force.
In U.S. Pat. No. 4,195,956 a parting tool with an exchangeable cutting insert is described, the design of said cutting insert is such that the insert can be clamped between two narrow jaws at the forward end of the blade holder which are positioned one exactly above the other. The upper jaw consists of a loose part which can be inserted into a recess in the holder and which is restrained from sideways movement. That upper part is arranged to be fixed in its position in the recess exclusively through the clamping effect created between the jaws and the clamped cutting insert. This clamping effect is brought about by the cutting forces which act on the cutting insert, which are taken up entirely by the jaws. Furthermore the upper jaw has an abutment for the rear surface of the cutting insert, whereby the cutting insert is clamped by pressing the cutting insert inwards into the insert pocket, whereby also the upper jaw is pushed rearwards and thereby the cutting insert is firmly clamped. This, however, results in the cutting edge not getting the well-defined radial positional accuracy which is desired. The cutting insert can therefore loosen when exposed to vibration. Further the different cross sections of the upper jaw (dovetail to the rear, edges with V-profile at the front) entail a complicated and inexact machining process.
Even U.S. Pat. No. 3,505,715 describes a tool for parting and the turning of grooves, which includes a loose clamp with which the insert is clamped. This clamp, however, has an inverted profile on its upper-respectively lower sides, which complicates manufacture of both the loose clamp and the slot for the clamp.
The prime purposes of the present invention are consequently to avoid costly changing of the complete holder and to simplify manufacture of a blade holder with a loose clamp.
Another purpose of the present invention is to develop a blade holder with a loose clamp, whereby two clamps which retain the insert are positioned in exactly the same plane, without risk of them becoming angularly displaced, in order to obtain a secure and rigid clamping with consistent positioning of the cutting edge particularly in the axial direction.